Theoretical analysis of true triaxial rock fracture mechanisms elucidates that the maximum ( \({\sigma _1}\) ) and intermediate ( \({\sigma _2}\) ) principal stresses predominantly govern macroscopic fracture orientation. To validate this principle, a computational framework simulating fracture evolution in randomly damaged thick-walled cylinders was established. Numerical experiments under three distinct principal stress regimes demonstrate that rotation of \({\sigma _1}\) and \({\sigma _2}\) directly dictates fracture plane orientation. Extending this concept to underground engineering, we propose a methodology for controlling fracture geometry in arched roadways: strategic adjustment of principal stress trajectories during excavation, combined with presplitting techniques to modify the local stress field around boreholes, effectively redirects fracture propagation in shoulder and corner zones. Results confirm the pivotal role of \({\sigma _1}\) - \({\sigma _2}\) plane alignment in rock fracture initiation and the directional dependence of surrounding rock fissures. This mechanistic insight provides critical guidance for structural stability optimization and disaster mitigation in deep underground projects.
